Information storage medium and method and apparatus for recording/reproducing data on/from the same

ABSTRACT

An information storage medium on which data is recorded after performing optimum power control (OPC) and a method and apparatus to record/reproduce data on/from the information storage medium, wherein the recordable information storage medium has a plurality of recording layers and a pickup irradiates a beam onto the information storage medium, utilize operations of: recording data on at least a portion of a recording layer through which a test beam to find an optimum recording power passes before performing optimum power control (OPC) on a desired recording layer and performing OPC on the desired recording layer. The method and apparatus allow data to be recorded after performing a test to determine an optimum recording power, thus providing effective recording/reproducing quality.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 11/005,099, filed Dec. 7, 2004, currently pending,which claims the priorities of Korean Patent Application No. 2004-14378,filed on Mar. 3, 2004 in the Korean Intellectual Property Office, KoreanPatent Application No. 2004-27575, filed on Apr. 21, 2004 in the KoreanIntellectual Property Office, and Korean Patent Application No.2004-43333, filed on Jun. 12, 2004 in the Korean Intellectual PropertyOffice, the disclosures of which are incorporated herein in theirentireties by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information storage medium and amethod and apparatus to record/reproduce data on/from the informationstorage medium, and more particularly, to a method and apparatus torecord/reproduce data on/from an information storage medium having aplurality of recording layers after performing optimum power control(OPC).

2. Description of the Related Art

An optical pickup performs non-contact recording/reproducing to/from aninformation storage medium. Optical disks that are one type ofinformation storage media are classified into compact disks (CDs) anddigital versatile disks (DVDs) depending on data recording capacity.Examples of optical disks capable of writing and reading informationinclude CD-Recordable (CD-R), CD-Rewritable (CD-RW), and 4.7 GB DVD+RW.Furthermore, a high Definition-DVD (HD-DVD) or blu-ray disk (BD) withrecording capacity of over 15 GB and a super-resolution optical diskthat may read data recorded in a pattern of marks below the resolutionlimit are currently being developed.

While only single layer 4.7 GB DVD-Recordable disks are commerciallyavailable, dual layer 8.5 GB DVD-ROM disks are being sold in the market.To back up data recorded on the 8.5 GB DVD-ROM disk, a DVD recordabledisk with the same capacity is required. Thus, to realize a need for arecordable disk having at least first and second recording layers, it ishighly desirable to have techniques for maintaining the samerecording/reproducing characteristics on a recordable informationstorage medium having a plurality of recording layers. One of the mostimportant recording/reproducing characteristics is called optimum powercontrol (OPC).

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus torecord/reproduce data on a recordable information storage medium havinga plurality of recording layers after performing optimum power control(OPC) and an information storage medium to which data is written by themethod.

According to an aspect of the present invention, a methodrecords/reproduces data on/from a recordable information storage mediumhaving a plurality of recording layers using a pickup. The methodincludes recording data on at least a portion of a recording layerthrough which a test beam for finding the optimum recording power passesbefore performing optimum power control (OPC) on a desired recordinglayer and performing OPC on the desired recording layer. The portion ofthe recording layer corresponds to tracks contained in the test beam.

Where SL, TP, NA, and n denote the thickness of a spacer layer betweenthe plurality of recording layers, a track pitch, a numerical apertureof an objective lens, and a refractive index of the information storagemedium, respectively, a number of tracks is determined using thefollowing equation:${{Number}\quad{of}\quad{Tracks}} = \frac{2{SL}\quad{\tan\left\lbrack {\sin^{- 1}\left( \frac{NA}{n} \right)} \right\rbrack}}{TP}$

Data may be recorded in an order of recording layers from closest tofarthest from the pickup.

When the plurality of recording layers include first and secondrecording layers and the first recording layer is located closer to thepickup, data may be recorded on a portion of the first recording layerthrough which the test beam passes before performing OPC on the secondrecording layer.

At least one of jitter, asymmetry, degree of modulation, or reflectivityis recorded on each recording layer.

According to another aspect of the present invention, an informationstorage medium comprises first and second recording layers, eithercontaining a lead-in area, a user data area, and a lead-out area,wherein data is recorded from the first recording layer to the secondrecording layer. In the information storage medium, the first and secondrecording layers respectively include OPC areas. Data is recorded on theinner or outer circumference of the OPC area in the first recordinglayer, and OPC is performed on a region of the OPC area in the secondrecording layer disposed opposite the region on which data is recordedto determine an optimum recording power.

In another embodiment of the present invention, a recordable informationstorage medium comprises a plurality of recording layers, wherein OPCinformation is stored indicating whether data has been written on aportion of a recording layer through which a test beam passes todetermine an optimum recording power for recording on a desiredrecording layer. In this case, the recording layers have an OPC area andthe OPC information contains information indicating whether data hasbeen written on inner or outer circumference of the OPC area. Each ofthe plurality of recording layers includes a lead-in area, a user dataarea, and a lead-out area, and the OPC information is recorded on atleast one of the lead-in area and the lead-out area. The lead-in areacontains a read-only region and a recordable region, and the OPCinformation is recorded on the recordable region.

According to another aspect of the present invention, an apparatusrecords/reproduces data on/from a recordable information storage mediumincluding a plurality of recording layers. The apparatus includes: apickup irradiating a beam onto the information storage medium; arecording/reproducing signal processor receiving a beam reflected fromthe information storage medium through the pickup for signal processing;and a controller detecting whether data has been recorded on a portionof a recording layer through which a test beam to determine an optimumrecording power passes and performs optimum power control (OPC) on adesired recording layer for recording through the pickup.

In another embodiment, the present invention provides an apparatus torecord/reproduce data on/from a recordable information storage mediumincluding a plurality of recording layers wherein the apparatus includesa pickup irradiating a beam onto the information storage medium, arecording/reproducing signal processor receiving a beam reflected fromthe information storage medium through the pickup for signal processing,and a controller to read information indicating whether data has beenrecorded on a portion of a recording layer through which a test beam todetermine optimum recording power passes and performs optimum powercontrol (OPC) on a desired recording layer to record through the pickupusing the information.

When data has not been recorded on the portion of the recording layer, apickup is controlled to record data on the portion of the recordinglayer through which the test beam passes to determine an optimumrecording power to record on the desired recording layer. Informationindicating that data has been recorded on the portion of the recordinglayer through which the test beam passes may be recorded on theinformation storage medium.

The information storage medium contains information indicating optimumrecording power conditions that may be applied when data is recorded onthe portion of the recording layer through which the test beam passesand when data is not recorded on the same. When the data is not recordedon the portion of the recording layer, OPC is performed using theoptimum recording power conditions instead of separately recording thedata to find the optimum recording power.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 illustrates a layout of a dual layer information storage mediumto illustrate a method to record/reproduce data on/from the informationstorage medium according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an apparatus to record/reproduce dataon/from an information storage medium according to an embodiment of thepresent invention;

FIG. 3 illustrates a layout of an information storage medium accordingto an embodiment of the present invention;

FIG. 4 illustrates another layout of an information storage medium onwhich disk related information has been recorded according to anembodiment of the present invention;

FIGS. 5A and 5B are layouts illustrating a method to perform a test onan information storage medium according to an embodiment of the presentinvention to determine an optimum recording power; and

FIGS. 6A and 6B are flowcharts illustrating processes of performing OPCin a method to record/reproduce data on/from an information storagemedium according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below to explain the presentinvention by referring to the figures.

A method to record/reproduce data on/from an information storage mediumhaving a plurality of recording layers according to an embodiment of thepresent invention allows data to be prerecorded on a portion of anotherrecording layer through which a beam passes when irradiating a targetrecording layer with the beam to find the optimum recording power.

A recordable information storage medium performs optimum power control(OPC) prior to recording data to determine an optimal recording power.To perform OPC, data is written in an OPC area at a predeterminedrecording power and read back to test the reproducing characteristics.Once the optimum recording power has been found during the test, data isrecorded at the optimum recording power during each recording session.

When OPC is implemented in a recordable information storage mediumhaving a plurality of recording layers, recording/reproducingcharacteristics exhibited after performing OPC may vary from onerecording layer to another, for example, depending on the recordingsequence or recording power. Since these variations may lead toinaccuracy in OPC, it is necessary to detect conditions that may causerecording/reproducing characteristics to change depending on the stateof each recording layer and perform OPC considering the conditions.

To find conditions that affect the recording/reproducingcharacteristics, experiments were made to write data on an informationstorage medium of FIG. 1, wherein the information storage medium hasfirst and second recording layers L1 and L2 in a different order and atdifferent recording power levels.

Recording conditions of the information storage medium are a linearvelocity of 3.8 m/s, laser wavelength of 650 nm, and objective lensnumerical aperture (NA) of 0.60. The information storage medium usesmultipulse write strategies. While a recording power of 15.1 mW, Ttop of1.45 T, Tmp of 0.65 T, and Tdtp 3T of −0.03T are used for the firstrecording layer L1, a recording power of 20 mW, Ttop of 1.65T, Tmp of0.70T, Tdtp 3T of −0.03T are used for the second recording layer L2.Ttop, Tmp, and Tdtp denote the duration of a top pulse, the duration ofeach pulse, and time shifted from a reference, respectively. Here, basicrecording conditions are set as recording power and write strategyadjusted for minimum jitter by writing data only on a desired recordinglayer, and 1T denotes 38.5 ns.

Table 1 shows jitter, I3/I14 modulations, asymmetries, andreflectivities measured after writing data on the first and secondrecording layers L1 and L2 under the above-mentioned conditions. Apickup is located closer to the first recording layer L1, and referencenumeral 10 denotes an objective lens. TABLE 1 First recording layer (L1)Second recording layer (L2) Recording Jitter I3/I14 Asym. Refl. JitterI3/I14 Asym. Refl. Recording state L1 7.9% 0.270 0.085 17.0% 8.1% 0.2550.030 17.5% L1 unrecorded, L2 unrecorded, recorded L2 recorded RecordingL2 8.0% 0.250 0.098 16.8% 8.3% 0.240 0.023 18.9% Recording L1 afterafter recording L2 recording L1 Recording L1 8.1% 0.267 0.091 16.5% 8.9%0.244 0.060 18.8% Recording L2 after after recording recording L1 L2

As is evident from Table 1, the first recording layer L1 maintainsalmost the same values of jitter, I3/I14, asymmetry (Asym.), andreflectivity (Refl.), regardless of the recording state or sequencewhile the second recording layer L2 exhibits varying characteristicsdepending on the recording sequence. That is, when data is writtensequentially from the first recording layer L1 to the second recordinglayer L2, the second recording layer L2 suffers from significantvariations in jitter, asymmetry, and reflectivity. When data is writtenin the reverse order, the second recording layer L2 suffers from lessvariations in such characteristics.

Table 2 shows recording/reproducing characteristics measured after datais written at recording powers that are 120% and 150% of the normalpower. During OPC, a test is performed at different recording powerlevels to determine an optimum recording power value. In particular,since the information storage medium once used for a predeterminedperiod of time may require a recording power higher than a normal powerdue to surface contamination, it is necessary to perform the test at ahigher power. TABLE 2 First recording layer (L1) Second recording layer(L2) Recording state Jitter I3/I14 Asym. Refl. Jitter I3/I14 Asym. Refl.Recording state Recording L1 8.2% 0.259 0.097 16.3% 9.3% 0.250 0.05218.8% Recording L2 after after recording recording L1 L2 (120%)Recording L1 8.2% 0.272 0.096 16.4% 9.8% 0.261 0.060 19.1% Recording L2after after recording recording L1 L2 (150%)

As is evident from Table 2, while the first recording layer L1 exhibitsalmost the same recording/reproducing characteristics even at higherrecording powers, the second recording layer L2 suffers from significantvariations in reflectivity, asymmetry, and jitter when data is writtensequentially on the first and second recording layers L1 and L2. Ascompared with recording at a normal power, the jitter increases, butreflectivity and asymmetry remain almost constant.

As may be seen in Tables 1 and 2 above, the first recording layer L1 islittle affected by a recording sequence or a recording power, whereasthe second recording layer L2 is significantly affected by the same. Inparticular, when data is written sequentially on the first and secondrecording layers L1 and L2, the second recording layer L2 suffers fromsignificant variations in the recording/reproducing characteristics.Such variations result from transmittance that may change, depending onwhether a recording beam passes through a recorded or unrecorded portionof a recording layer. Low transmittance reduces the effect of therecording power.

Meanwhile, it is necessary to perform a test under the conditions thatcause significant variations in recording/reproducing characteristics.That is, if there is insignificant change in the recording/reproducingcharacteristics under any conditions, it is possible to find theaccurate optimum recording power without any special test conditions fordetermining the same. However, if the recording/reproducingcharacteristics vary according to the recording conditions, a test needsto be performed under conditions that cause significant variations inthe characteristics to determine the optimum recording power.

Thus, when a test beam is emitted to find the optimum recording power,generally, data has been written on at least a portion of a recordinglayer through which the test beam passes.

Referring to FIG. 2, an information storage medium D includes a firstrecording layer L1 and L2, and a pickup 50 to record data is disposedbelow the first recording layer L1. Before a test beam is irradiated toperform OPC on the second recording layer L2, data is recorded on aportion of the first recording layer L1 through which the test beampasses. In this case, data may be recorded in an area corresponding totracks contained in the beam irradiated on the first recording layer L1.

Referring to FIG. 1, the number of tracks contained in the portion ofthe first recording layer irradiated by the test beam is given byEquation (1): $\begin{matrix}{{{Number}\quad{of}\quad{Tracks}} = {\frac{2X}{TP} = \frac{2{SL}\quad\tan\quad\theta}{TP}}} & (1)\end{matrix}$where SL and TP denote the thickness of a space layer 15 between thefirst and second information storage layers L1 and L2 and a track pitch,respectively.

Where n is a refractive index of the information storage medium and NAis a numerical aperture of the objective lens 10, using the relationalexpression NA=n sin θ, Equation (1) is summarized as: $\begin{matrix}{{{Number}\quad{of}\quad{Tracks}} = \frac{2{SL}\quad{\tan\left\lbrack {\sin^{- 1}\left( \frac{NA}{n} \right)} \right\rbrack}}{TP}} & (2)\end{matrix}$

Data may be written on an area of the first recording layer L1corresponding to the number of tracks defined by Equation (2) beforeirradiating a test beam for OPC onto the second recording layer L2.

Where SL tan θ=41.25 (μm) and TP=0.74 μm, the number of tracks containedin the test beam is about 112.

In the case of a DVD-ROM drive, a pickup is disposed below a firstrecording layer and data is written from the first recording layer tothe second recording layer. To maintain consistency with the DVD-ROMdrive, the recordable information storage medium may be designed toallow data to be written from the first recording layer L1 to the secondrecording layer L2.

The same method to record/reproduce data according to an embodiment ofthe present invention may apply when the pickup is located above thesecond recording layer L2. In this case, data is first recorded on thesecond recording layer L2. Before performing OPC for recording on thefirst recording layer L1, data is recorded on at least a portion of thesecond recording layer L2 through which a test beam passes.

Furthermore, the method may be applied to both opposite track path (OTP)and parallel track path (PTP) disks. While the present invention hasbeen described with reference to a dual layer information storagemedium, the method may also apply to a multi-layer medium having threeor more recording layers.

Meanwhile, to obtain the optimum recording power, at least one ofjitter, degree of modulation, asymmetry, and reflectivity for eachrecording layer is recorded on each recording layer. Referring to FIG.3, an information storage medium according to an embodiment of thepresent invention includes a lead-in area 20, a user data area 25, and alead-out area 30.

The lead-in area 20 is divided into a read-only region and a recordableregion, and a control data zone in the read-only region contains diskrelated information and copy protection information, either of which maybe used to perform OPC.

At least one of jitter, degree of modulation, asymmetry, or reflectivityfor each recording layer is recorded in predetermined bytes in thecontrol data zone. In particular, a recordable information storagemedium may include asymmetry information. Asymmetry for the secondrecording layer may be measured after data is recorded on a portion ofthe first recording layer through which a beam passes when the beam isemitted from below the first recording layer.

When the material or the type of the information recording mediumchanges, control information such as asymmetry, degree of modulation,and jitter may be recorded together. The control information may berecorded on either or both of the lead-in and lead-out areas 20 and 30.

Alternatively, referring to FIG. 4, asymmetry information about firstand second recording layers each may be recorded on a different space inthe control data zone. In this case, while the asymmetry informationabout the first recording layer is recorded along with informationrepresenting layer number, i.e., the first recording layer, theasymmetry information concerning the second recording layer is recordedalong with information representing the second recording layer. The diskrelated information may be recorded in the same way on both the firstand second recording layers.

Referring to FIG. 5A, first and second recording layers L0 and L1respectively include first and second OPC areas L0-23 and L1-23. Aregion 21 b of the first recording layer L0 on which OPC is performed isnot disposed opposite a region 22 a of the second recording layer L1 onwhich OPC is performed. When a beam is incident through the firstrecording layer L0, data is prerecorded on a region 21 a disposeddirectly below the region 22 a before performing OPC on the secondrecording layer L1.

A region 22 b of the second recording layer L1 disposed opposite theregion 21 b of the first recording layer L0 subjected to OPC may beallocated for a reserved area. For recording onto the region 21 a of thefirst recording layer L0 through which a beam to perform OPC on thesecond recording layer L1 passes, a prerecording process may beperformed during fabrication of a disk, or data may be recorded in apredefined manner on a predetermined region of the first recording layerL0 prior to recording of user data.

Referring to FIG. 5B, first and second recording layers L0 and L1respectively include first and second OPC areas L0-23 and L1-23. While aregion 21′a of the first recording layer L0 where OPC is performed ispositioned on the inner circumference of the first OPC area L0-23, aregion 22′b of the second recording layer L1 where OPC is performed islocated on the outer circumference of the second OPC areas L1-23.

When a beam is incident through the first recording layer L0, data isprerecorded on a region 21′b disposed directly below the region 22′bbefore performing OPC on the second recording layer L1.

A region 22′a of the second recording layer L1 disposed opposite theregion 21′a of the first recording layer L0 subjected to OPC may be areserved area. The same recording mechanism may apply to the outercircumference of the information storage medium as well as the innercircumference.

Referring to FIG. 6A, a method to perform OPC for each recording layerin an information storage medium having a plurality of recording layersincludes performing OPC on a recording layer from the lowermostrecording layer upward when the information storage medium is insertedinto a drive, and recording user data on the same recording layersubjected to OPC before performing OPC on an overlying recording layer.In this case, after recording on a first recording layer, OPC isperformed on a second recording layer. However, since the method allowsuser data to be input continuously during OPC for the second recordinglayer, a memory or buffer is required to store a predetermined amount ofdata until OPC is finished.

Referring to FIG. 6B, an alternative method to perform OPC for eachrecording layer includes sequentially performing OPC on each recordinglayer when the information storage medium is inserted into the drive,and sequentially recording data on each recording layer. This methoddoes not require a memory or buffer and is advantageous in continuouslyrecording data without interruption.

Referring to FIG. 2, an apparatus (i.e., a disk drive) torecord/reproduce data on/from the information storage medium D accordingto an embodiment of the present invention includes a pickup 50, arecording/reproducing signal processor 60, and a controller 70. Morespecifically, the pickup 50 includes a laser diode 51 that emits a beam,a collimating lens 52 that collimates the beam emitted by the laserdiode 51 to a parallel beam, a beam splitter 54 that changes thepropagation path of an incident beam, and an objective lens 56 thatfocuses the beam passing through the beam splitter 54 onto theinformation storage medium D.

The beam reflected from the information storage medium D is reflected bythe beam splitter 54 and is incident on the photodetector 57 (e.g., aquadrant photodetector). The beam received by the photodetector 57 isconverted into an electrical signal by an operational circuit 58 andoutput as a RF or a sum signal through channel Ch1 and as a push-pullsignal through a differential signal channel Ch2.

Before recording data on the information storage medium D having thefirst and second recording layers L1 and L2, the controller 70 performsa test on a test area in the information storage medium D to determinethe optimum recording power. To achieve this function, after recordingdata on the first recording layer L1, the controller 70 detects whetherdata has been written on a portion of the first recording layer L1irradiated by a test beam during an OPC test for the second recordinglayer L2 and controls the pickup 50 to record data on at least a portionof the first recording layer L1 through which the test beam passesbefore performing the test.

During the OPC test, the controller 70 also reads control informationsuch as reflectivity, jitter, degree of modulation, or asymmetry throughthe pickup 50 and determines the optimum recording power using thecontrol information. Then, the controller 70 allows a recording beam tobe irradiated from the pickup 50 at normal power obtained during thetest, so that data can be recorded on the information storage medium Dusing the recording beam.

To reproduce the thus recorded data, a beam reflected from theinformation storage medium D passes through the objective lens 56 andthe beam splitter 54, and is incident on the photodetector 57. The beaminput to the photodetector 57 is then converted into an electricalsignal by the operational circuit 58 and output as an RF signal.

A drive according to another embodiment of the present invention mayinclude OPC information on an information storage medium. For example,the OPC information may contain information on an effect on the OPC dueto whether data has been recorded on a portion of the informationstorage medium through which a beam passes during OPC. The drive havingsuch information eliminates a need to prerecord data on an area of theinformation storage medium through which a beam passes during OPC.

That is, in this embodiment, the drive having the OPC information doesnot require data to be recorded on an adjacent recording layer of theinformation storage medium before OPC. Recording data on the informationstorage medium for OPC, even in a drive having OPC information, mayincrease data recording time and reduce an OPC area due to datarecording.

Thus, by providing predetermined information with a drive having OPCinformation, recording data on an adjacent recording layer for OPC isunnecessary. Therefore, by using the predetermined information, thedrive may perform OPC accurately and quickly using embedded OPCinformation, even if data has not been written on a portion throughwhich a beam for OPC passes.

For example, let a drive possessing OPC information representing aneffect on the OPC due to whether data has been recorded on an areathrough which a beam for OPC passes be a drive A, let a drive having nosuch information be a drive B, and let the area irradiated with a beamfor OPC be an area Y.

To record data on the information storage medium, the drive A reads diskrelated information before performing OPC. In this case, wheninformation indicating that data has been written on the area Y throughwhich a beam for OPC passes is not recorded on the information storagemedium, the drive A performs OPC using its embedded OPC informationwithout the need to record separate data on the area Y, thus saving timespent in recording data on the area Y. Conversely, when informationindicating that data has been written on the area Y is recorded on apredetermined area of the information storage medium, the drive Aperforms OPC at recording power that is adjusted considering that datahas been written on the area Y.

To record data on the information storage medium, the drive B reads diskrelated information and information written on a recordable regionbefore performing OPC. In this case, when information indicating thatdata has been written on the area Y is not recorded on the informationstorage medium, the drive B first records data on the area Y of theinformation storage medium before performing OPC. When performing OPC,the drive B irradiates the area Y with an OPC beam and then recordsinformation indicating that data has been written on the area Y on arecordable region (e.g., an information zone) in a lead-in area or alead-out area.

For example, to perform OPC on a second recording layer, informationindicating whether data has been written on the area Y of a firstrecording layer may be recorded as follows, using a byte X in theinformation zone:

-   -   Byte X: 0000 0000(00h)-->Not recorded        -   0000 0001(01h)-->Recorded

Meanwhile, information on whether OPC data has been written on inner orouter circumference of the OPC areas L0-23 and L1-23 as shown in FIGS.5A and 5B may be recorded as follows, using X bytes:

-   -   Byte X: 0000 0000(00h)-->Not recorded on inner and outer        circumferences,        -   0000 0001(01h)-->Not recorded on inner circumference,            recorded on outer circumference        -   0001 0000(10h)-->Recorded on inner circumference, not            recorded on outer circumference        -   0001 0001(11h)-->Recorded on inner and outer circumferences

As described above, the first four bits of one byte representinformation on the inner circumference, and the following 4 bitsrepresent information on the outer circumference. Alternatively, eitherinformation may be recorded using two bytes.

Specifically, an information storage medium includes first and secondrecording layers L0 and L1, and data is recorded from the firstrecording layer L0 to the second recording layer L1. A pickup may belocated below the first recording layer L0. A drive may use informationon whether data has been separately written on an area through which atest beam for OPC passes in performing OPC to record on the secondrecording layer L1. If the information for OPC has not been written tothe area, the drive may perform OPC using its embedded OPC informationinstead of separately recording OPC data.

The same method may be applied to a multi-layer information storagemedium having three or more recording layers. In this case, when arecording layer being subjected to OPC is irradiated with a test beam,information indicating whether data has been written on an area throughwhich the test beam passes is recorded on a predetermined region of theinformation storage medium, and OPC is performed on the plurality ofrecording layers using the same information.

Here, an OPC test zone may be disposed in an area other than a user dataarea. While FIGS. 3 and 4 illustrate that the lead-in area 20 containsthe test zone, a test area may be positioned separately from lead-in andlead-out areas.

Meanwhile, when information indicating that data has been written on thearea Y is recorded on a predetermined area of the information storagemedium, the drive B performs OPC at recording power that is adjustedconsidering that data has been written on the area Y.

A drive according to an embodiment of the present invention controls thepickup 50 to read information concerning whether data has been writtenfor OPC and perform OPC in a manner specific to the drive.

An information storage medium according to an embodiment of the presentinvention contains information indicating whether data has been recordedon an area through which a beam for OPC passes, thus making recording ofseparate data for OPC optional according to the type of a drive. A drivepossessing OPC information performs OPC without a need to recordseparate data, thus reducing the recording time and increasing theutilization efficiency of an OPC area.

A method to record/reproduce data on/from the information storage mediumaccording to an embodiment of the present invention enables determiningan optimum reading power to record/reproduce data to/from a recordableinformation storage medium having a plurality of recording layers. Themethod requires a test to find the optimum recording power forrecording, thus achieving effective recording/reproducingcharacteristics. The present invention allows data to berecorded/reproduced in an order of recording layers from closest tofarthest from a pickup, thus providing a recordable information storagemedium capable of achieving consistency with a DVD-ROM.

The present invention also provides an apparatus to record/reproducedata on the information storage medium to perform a test on a desiredrecording layer to find the optimum recording power.

The present invention also provides information on recording of dataneeded for OPC so as to select recording conditions for OPC according toa type of a drive, thus enabling more efficient OPC.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A method of reproducing data from an information storage medium,comprising: irradiating a beam onto an information storage medium, theinformation storage medium having a plurality of recording layers; usingthe irradiated beam to read data from the information storage mediumrecorded according to an optimum power control (OPC) determinedaccording by recording other data on at least a portion of a recordinglayer through which a test beam to find an optimum recording powerpasses; and performing the optimum power control (OPC) on apredetermined recording layer; and reproducing the read data.
 2. Themethod of claim 1, wherein the portion of the recording layercorresponds to tracks contained in the test beam,${{Number}\quad{of}\quad{Tracks}} = \frac{2{SL}\quad{\tan\left\lbrack {\sin^{- 1}\left( \frac{NA}{n} \right)} \right\rbrack}}{TP}$wherein SL, TP, NP, and n denote a thickness of a spacer layer betweeneach of the plurality of recording layers and a next recording layer, atrack pitch, a numerical aperture of an objective lens, and a refractiveindex of the information storage medium, respectively.
 3. The method ofclaim 1, wherein data is recorded in an order of recording layers fromclosest to farthest from an pickup performing the irradiating.
 4. Themethod of claim 1, wherein: the plurality of recording layers comprisesfirst and second recording layers, the first recording layer is locatedcloser to the pickup than the second recording layer, and the other datais recorded on a portion of the first recording layer through which thetest beam passes before performing OPC on the second recording layer. 5.The method of claim 1, wherein control information to perform OPC isrecorded on at least one of a lead-in area and a lead-out area in theinformation storage medium.
 6. The method of claim 5, wherein thecontrol information includes at least one of jitter, asymmetry, degreeof modulation, or reflectivity.
 7. The method of claim 6, wherein thecontrol information is measured after recording data on the portion ofthe recording layer through which the test beam passes.
 8. The method ofclaim 1, wherein information indicating that the data has been writtenon the portion of the recording layer through which the test beam passesis recorded.
 9. The method of claim 1, wherein: the plurality ofrecording layers comprises first and second recording layers, the firstand second recording layers respectively comprise OPC areas, and thedata is recorded on the inner or outer circumference of the OPC area inthe first recording layer and OPC is performed on a region of the OPCarea in the second recording layer disposed opposite the region on whichdata is recorded to determine an optimum recording power.
 10. The methodof claim 1, wherein information indicating that the data has beenwritten on the portion of the recording layer through which the testbeam passes is recorded.
 11. The method of claim 9, wherein the OPC areais positioned separately from a lead-in area and a lead-out area of thefirst and second recording layers.
 12. The method of claim 1, whereinthe recording layers have an OPC area, and OPC information is recordedwhich includes information indicating whether the data has been writtenon an inner or an outer circumference of the OPC area through which thetest beam passes.
 13. The method of claim 12, wherein each of theplurality of recording layers comprises a lead-in area, a user dataarea, and a lead-out area, and the OPC information is recorded on atleast one of the lead-in area and the lead-out area.
 14. The method ofclaim 13, wherein the lead-in area comprises a read-only region and arecordable region, and the OPC information is recorded on the recordableregion.